How accurate are motorcycle fuel gauges?

fuel gauges

Why are some fuel gauges and fuel-range indicators sometimes so inaccurate they leave riders stranded with an empty tank far from a service station?

In fact, often the more hi-tech, sophisticated and expensive machinery can have the most fickle fuel gauges.

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Common errors

The most common error is that the fuel gauge and/or range-to-empty indicator fail to reset after refuelling.

This often happens if you don’t refuel all the way to the top.

Another problem is inaccurate readings after topping up a tank that was only partially empty.

It seems the reason is that the fuel level “sender” does not go to the top of the tank.

That means it can’t properly measure the fuel because it doesn’t account for the fuel in the top of the tank.

It only works properly when the fuel level has dropped below the sender and the tank is then filled up completely.

Anything else and it gets confused.

For example, if you top up the fuel before it gets to the sender or if you don’t fill to the top when the fuel has dropped below the sender.

Turning the bike off and on again makes no difference to the gauges or range indicator.

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Refuelling the MBW machine in Mexico!

Alternative gauges

Neither of my bikes – a 2010 Triumph Scrambler and a 2006 Ducati GT1000 – has fuel gauges. The Scrambler’s low-fuel warning light doesn’t even work!

Instead, I reset the trip meter when I fill up and I know I will get about 200km out of the tank before needing to search for a service station.

However, I have still run out of fuel on the Scrambler.

There is something to be said about the old low-tech system of a petcock valve to switch to the reserve tank when the engine starves of fuel! (Just remember to return it to “on” after refuelling.)

fuel gauges
Old-school petcock

Or maybe an old unlockable fuel cap you can unscrew so you can see inside the tank!

While some people are suspect about technology, one of the most convenient pieces of modern technology is the GPS unit that shows distance to the nearest fuel station.

  • Have you ever embarrassingly run out of fuel? Read our story and then tell us yours! 

9 Comments

  1. My CanAm Spyder has a very consistent fuel gauge, by that I mean that the readings are consistent but horrendously inaccurate… 1/8th of a tank on the gauge is actually half full. I’ve just learned to keep an eye on the position of the needle and not read the associated scale.
    Whenever I fill up I reset my GPS which will then throw up a warning on the screen 300km later to tell me it’s time to go and look for a bowser.
    I agree with Scott – look at the computational power in the world today and then look at the piddly accuracy of automotive gauges – like the Professor used to say, “Why is it so?”

  2. After 60 yrs of riding I cant remember all those times I ran out of fuel.

    Ah!! In those days of My Youth I could lean the bike at a angle to get the last dregs to the petcock then go on my merry way to a Servo.

    Of late I’ve had six Triumph Tigers (1050s and 800s), all have fuel gauges, but my latest 800’s fuel gauge light comes on with about 6lts left in the tank!

    When man can set foot on the Moon (many years ago) why can’t a 2016 motorcycle fuel gauge be accurate? My Beemer estate’s fuel gauge is very accurate.

    I’ve taken the sender unit out of the tank (not recommended if you have big hands like mine) and tried to adjust it … no way.

    And looking into the tiger tank, all one see is the top of the Fuel Pump casing.

    I used to carry a 2.5lt can as a spare fuel source until it sprang a leek and there I was riding around with 2.5lts of fuel in my Top Box .

    I found out that my RJay Top Box is waterproof, very well sealed against dust and fuel fumes.

  3. My first bike didn’t even have a fueltank, made a nailhole in the bottom of a lawnmower fuel can & ockystrapped it to the frame above the carby, dripfeed straight into the floatbowl, stuck a twig in the hole when parked, young people have it easy nowdays ABCD brakes, padded seats, rear suspension, cold beer, bunch of softies if you ask me

  4. I ran out of fuel, on my Speedmaster in the Airport link tunnel in Brisbane two months ago. So embarrassing as I have never run out of fuel before.
    The low fuel warning light failed to work and I thought I had enough to make it to the garage just past the exit.
    I started pushing the bike when over the PA system in the tunnel, I was advised to stay where I was and help was on its way. Tunnel control closed the lanes on my side and within two minutes, two tow trucks turned up, one parked beside me and the other behind me to protect me!
    The two blokes in the tow trucks where fantastic and were going to load me up but when I said I was out of fuel, they gave me ten litres of premium fuel and I was on my way no charge!

    Great service!

  5. The only time I ran out of fuel on a bike is when I forgot to turn my BMWs petcock valve back from the reserve tank after turning to the reserve on an earlier ride, wouldn’t you just know it? Luckily I wasn’t far from a service station. Nowadays I always turn the fuel off on that bike when I get home so I have to turn the fuel back on before riding AND I reset the trip meter after filling. As it is a 1980s bike it doesn’t have a fuel gauge.
    On my newer Indian I have a 20.8 litre tank with an estimated range of 340 km or thereabouts (I don’t want to run it out just so I know exactly). I use the gauge, the digital readout showing kilometres remaining and the trip meter but always look to fill up at the 250 to 280 km mark. The most irritating thing about the Indian is when the the tank is getting low the kilometres remaining changes from a number to “low fuel” when about 65 kms remaining, irritating? Sure is, it isn’t also very helpful when I’m 40 kms from the nearest fuel as I find I keep looking at the d**n thing expecting to stop any moment even though logic tells you you have plenty of fuel. The letdown (or sense of relief) is then to finally get to the fuel station and only put 18 litres in the tank.
    Still, the fun of riding any bike still doesn’t go away, so with or without an accurate gauge the riders best friend is the trip meter and common sense.
    One product that did interest me is a low volatile emergency fuel called “Magic Tank” which I read about a year or so ago but it isn’t available in Australia as far as I can find out and the engine still has to be warm for it to start using this fuel. I am sure that buying it online wouldn’t thrill our postal service even if they were assured that it was low risk.

    1. If you bought it online when you were sitting at side of road run out of fuel, how long would it take to be delivered to your bike?

      1. The “Magic Tank” fuel has a shelf life of 10 years as it excludes the chemicals that make fuel go off, so you could carry it with you in situations when you are unsure about availability of refilling stations. At least it could give a safer emergency fuel than carrying possibly explosive fuel.

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